In a mechanical seal serving as one example of the sliding parts, performances thereof are evaluated by a leakage amount, a wear amount, and torque. In the prior art, the performances are enhanced by optimizing sliding material and sealing face roughness of the mechanical seal, so as to realize low leakage, long life, and low torque. However, due to raising awareness of environmental problems in recent years, further improvement in the performances of the mechanical seal is required, and there is a need for technical development going beyond the boundary of the prior art.
There is a known technique in which by respectively partitioning a plurality of cyclic structures discretely formed on a sealing face by mirror face parts and damming both ends of recess parts of grating shape recesses and projections of the cyclic structures by the mirror face parts, an oil film retaining ability in the cyclic structures is increased, so that a reciprocating sliding characteristic and a rotating sliding characteristic are improved (for example, refer to Patent Citation 1. Hereinafter, the technique will be called as the “prior art”).